Torque equalizer for counterrotating propellers



Patented Feh. 5, 1952 UNITED STATES ATNT OFFICE TORQUE EQUALIZER FOR COUNTER- ROTATING PROPELLERS 12 Claims.

(Granted under the act of: March a, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates toan improved drive and pitch changing mechanism for counterrotating tandem propellers for a torpedo, aircraft or the like and more particularly to a mechanism of this character for automatically adjusting the pitch. and speed of the blades of one propeller relative to the other sufficiently to equalize the torques applied: to each of the propellers.

It is. well known that where a. single propeller is employed the tractive or propulsive torpedo propeller imparts to the driving shaft a reaction torque which which is due to the action of the water streams and the pressure of ,the water upon the propeller blades. This torque depends upon the direction of the water streams with reference to the blades, that is, upon the pitch and speed of rotation of the propeller and of the velocity of the surrounding water with reference to the torpedo, which depends in turn upon the speed of translation of the torpedo. This reaction torque is known as a permanent heel which is the tendency of the torpedo to roll on its longitudinal axis a fixed amount and run with its vertical axis at an angle with respect to its true vertical plane. This permanent heel interferes with the steering mechanism of the torpedo to cause it to deviate from the desired course.

The superior efficiency of counterrotating tandem propellers over a singlepropeller designed to absorb the same power is well known and the desirability of being. able to automatically change the thrust of the blades of one. propeller sufficiently to equalize the torques on each propeller is recognized by those skilled in the art.

In certain of the mechanisms of this character. heretofore devised the pitch of the bladesof both propellers have been equally and simultaneously changed with the undesirable result that unequal torques. are applied to the propellers.

One of the objects of the present invention is to provide a closely integrated driving and pitchchanging unit in which the pitch-changing mechanism is rotary; coaxial with the rotary driving mechanism and nested with respect thereto.

Another object of the invention is to prvoide a driving and pitch-changing unit having an unlimited range of pitch adjustment.

Still another object of the invention is to provide a combined pitch-changing and driving unit for counterrotating tandem propellers which automatically adjusts the pitch of one propeller to equalize the torques applied to both propellers.

An additional object resides in the provision of a combined pitch-changing; and differential driving unit for counterrotating tandem propellers wherein the pitch of" the blades of one propeller is automatically adjusted ina direction to equalize the torques on the propellers in response to a difference in the speeds of the propellers.

Still other objects, advantages and improve.- ments will be apparent from the following description, taken inconnection with the accompanying drawing in which the single figureofthe drawing shows a longitudinal section through. a. combined driving and pitch-changing unit. embodying the principles of the present invention.

Referring now to the figure of the drawing which is a longitudinal sectional view of the mechanism, the numeral It! represents the engine housing having a pair of stub shafts 25 and 28 secured thereto upon which are rotatably mounted bevel gears 21' and 28 respectively. The drive shaft: l I driven from a prime mover is provided with a cross head I2 having a pair of stub shafts I3 and It integrally formed. thereon.

Extending from the cross head I2 in axial alignment with driveshaf-t I I, is the pitch changing shaft I5, having aflixed to its end in. any well known manner, a bevel gear I6, shaft. I5 preferably being formed integrally with. the cross head I2. Bevel gear I6 is employed to change the pitch of thepropeller blades I! which, for this purpose, are rotatably mounted in the tubular hub 35 of the propeller generally designated 3?, blades. I'I being formed at their inner ends with stub shafts 35 rotatably mounted in apertures therefor provided in the hub. The stub shafts 35 respectively have the gears I8. and I9 fixedly secured thereto. These gears are in mesh with the gear I 6, thereby to complete a pitchchanging connection between the pitch-changing shaft 15 and propeller blades H.

A pair of bevel gears 2I and 22, rotatably mounted on stub shafts I3 and I4 respectively, are meshed with bevel gears 23 and 24 respectively. Gear 23, which is also in mesh with gears 2'! and 28, is interposed between cross head I2 and collar 34 and is free to rotate on the drive shaft II. Gear 23 forms a part. of a difierential gear drive comprising gears 2|, 22 and 24 and drives bevel gear 32 through reverse gears, 21 and 23 in the opposite direction with respect to the direction of rotation of the drive shaft.

Fixed pitch propeller blades 29 and the hub therefor comprise the propeller generally designated 38 and secured to the tubular propeller shaft SI, which. shaft, in turn, is secured as by a key Al to propeller 38. The hub 36 of the vari- 3 able pitch propeller 31 is fixed to the tubular propeller shaft 33 as by the key 39 which, in turn, is secured to bevel gear 24 in any well known manner, as by a key, for example.

It will be observed that the propeller shafts 3| and have the form of sleeves, one rotating upon the other about the pitch-changing shaft l5.

By reason of the differential drive and reversing gears 21 and 28, as stated hereinbefore, gear 32 and therefore the propeller shaft 3| and propeller 38 operatively connected thereto are driven in the opposite direction from drive shaft II. By reason of the differential drive, gear 24 and therefore propeller shaft 33 and the variable pitch propeller 31 operatively connected thereto are driven in the same direction as the drive shaft. As there is no change in speed ratio in the reversing gears, both propellers will travel at the same speed as the pitch changing shaft I5 when equal torque is applied to both propellers.

If the torque applied to the propellers becomes unequal, the propeller shafts 3| and 33 will travel at. different speeds from the speed of the pitchchanging shaft l5 whereby the pitch of propeller blades I 1 will be changed through gears I 6, l8 and 19 in a direction to equalize the torque on propeller shafts 3| and 33. When the torque is equalized, thespeeds of the propeller shafts become equal to the speed of the pitch-changing shaftwhereupon no further adjustment of the blades [1 occurs. The manner in which this resultis accomplished will become clear from the following examples.

Assuming that drive shaft H is rotating, and assuming further that propeller 38 has a greater torque. thereon than propeller 3T, propeller 38 will rotateat a lesser speed and propeller 3'! will travel at a greater speed than the speed of pitchchanging. shaft [5. As propeller 31 rotates ahead of shaft l5, gears l8 and I9 rotate on gear I6 to increase the pitch of blades I1 and therefore the torque on propeller 31 until the torque applied to the propellers becomes equal. Assuming that the torque on propeller 38 becomes less than the torque on propeller 31, propeller 31 now runs at a lesser speed than shaft l5 whereupon gears l8 and i9 rotate on gear IS in a direction to decrease the. pitch of blades IT, thereby to decrease the torque on propeller 31 and increase the speed thereof until the speed equals the speed of shaft I5, In either case, as the torque on propeller 31 is increased or decreased as the pitch of blades I1 is increased or decreased selectively, the torque on propeller 38 becomes changed by inversely proportional amounts in a manner well known to those familiar with differential drives.

It will be understood that in some cases it may be desirable to employ stops to prevent rotation of blades l'| beyond 90 in order to avoid reversing the direction of thrust of propeller 31. It may also be desirable to employ any suitable means for damping the pitch-changing drive to prevent overshooting of the pitch adjustment.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A propeller driving system for a torpedo comprising, in combination, a pair of propellers, one of said propellers having variable pitch blades, a pair of coaxially disposed propeller shafts individual to said pair of propellers, a drive shaft coaxially arranged with respect to said propeller shafts and having a speed changing shaft connected coaxially thereto and extending within said propeller shafts, driving connections including differential gearing between said drive shaft and said pair of propeller shafts for driving the propellers in opposite directions and at the speed of the drive shaft when the propellers have equal torques applied thereto, one of the propeller shafts being driven in same direction as the drive shaft, and gear connections between said variable pitch blades and the speed changing shaft and responsive to a difference in speed of rotation between the drive shaft and said one of the shafts due to unequal torque on the propellers for adjusting the pitch of the blades sufficiently to equalize the torques on the propellers thereby to bring the speed of said one of the propellers into conformity with the speed of rotation of the drive and speed changing shafts.

2. A driving and torque equalizing arrangement for counterrotating propellers comprising, in combination, a power imparting drive shaft having a gear mounted thereon, an outer propeller shaft and an inner propeller shaft each concentrically mounted for rotation about a portion of said drive shaft, said outer propeller shaft having fixed pitch propeller blades, said inner propeller shaft having variable pitch propeller blades, each of said variable pitch blades being rotatable about the pitch axes individual thereto and having propeller blade gear respectively secured thereto in meshed engagement with said gear on said drive shaft, differential gearing between the inner propeller shaft and the drive shaft for driving the inner propeller shaft in the direction of the drive shaft, and reverse differential gearing between the outer propeller shaft and the drive shaft for driving the outer propeller shaft in a reverse direction from the drive shaft, said differential gearing between the drive shaft and the propeller shafts causing the propeller shafts to rotate at different speed when the torques thereon are unequal therebyto cause sufficient relative rotation between said drive shaft gear and said propeller blade gears to adjust the pitch of the variable propeller blades until the speeds and torques of the propeller shafts are equalized.

3. A torque equalizer for counterrotating. propellers comprising, in combination, a power imparting drive shaft, a pair of shafts coaxially arranged about said drive shaft, a pair of oppositely pitched propellers mounted individually on adjacent ends of said pair of shafts for rotation therewith, the blades of one of said propellers being rotatable about their pitch axes and having propeller blade gears respectively secured thereto to effect change of pitch rotation thereof, differential gearing for driving one of said pair of shafts from the drive shaft in the direction of the drive shaft, differential gearing including reverse gears for driving the other one of said pair of shafts from said drive shaft in the opposite direction thereto, said drive shaft having a drive gear secured coaxially thereto for rotation therewith and arranged to mesh with said propeller blade gears, said difierential gearing causing speed differentials-betweensaid pair of shafts and said drlve shaftmandrelative rotation between said drive shaft gear and propeller'blad'e gears when the torques on the propellers are unequal, thereby" to adjust the pitch of said rotatable blades sufficiently to equalize the torques on said pair of shafts and bring the speed of said pair of shafts into conformity with the speed of the drive shaft.

45. In a torpedo driving system comprising, in combination, a drive shaft and inner and outer propeller shafts coaxially arranged with respect to said drive shaft, the end of the inner propeller shaft projecting beyond the end of the outer propeller shaft, propellers with oppositely pitched blades mounted on the adjacent ends of said in her and outer propeller shafts respectively for rotation therewith, each of the propeller blades on the inner propeller shaft being rotatable about its pitch axis, a drive gear coaxially secured to the end of said drive shaft, 2. pair of driven propeller pitch gears secured respectively to said rotatable blades and arranged in mesh with said drive shaft gear, and-driving connections including differential gearing between said drive shaft and said inner and outer propeller shafts for respectively driving the inner and outer propeller shafts in the same and opposite directions respectively to the direction of rotation of the drive shaft and at the speed of the drive shaft when equal torques are applied to the propeller shafts whereby a difierence in speed between the propeller shafts due to unequal torques thereon causes relative rotation between said drive shaft gear and said propeller gears to adjust the pitch of the blades sufficiently to bring the speed of the propellers into conformity with the speed of the drive shaft.

5. A speed equalizing mechanism for counterrotating propellers comprising, in combination, a pair of tandem propellers, one of said propellers having variable pitch blades, a power imparting drive shaft, driving connections including differential gearing between said drive shaft and said pair of propellers for driving the propellers in A opposite directions and at a speed equal to the speed of the drive shaft when the propellers have equal torques applied thereto, pitch changing connections including a plurality of bevel gears between said variable pitch blades and said drive shaft and responsive to a difierence in speed be tween the drive shaft and said propellers due to unequal torque applied thereto for varying the pitch of the blades independently of the speed of the other of said propellers and sufficiently to equalize the torque applied to the propellers thereby to adjust the speed of the propellers to equal the speed of the drive shaft.

6. A torque equalizer for counterrotating propellers comprising. in combination, a first propeller having a hub and a plurality of blades mounted to rotate in the hub individually about their pitch axes, a second propeller having a hub and a plurality of blades formed integrally therewith, a pair of coaxial propeller shafts individual to said pair of propellers and secured to the hubs thereof, pitch adjusting means on said first hub individual to the blades thereon, each of said pitch adjusting means comprising a pinion fixed on hub end of the blade individual thereto, a drive shaft coaxially arranged with respect to said propeller shafts, a gear coaxially secured to said drive shaft in meshing engagement with the blade pinions, differential driving connections between said drive shaft and said pair of propeller shafts for driving the propellers in opposite dimotions and at the speed of thedriveshaftwhen the propellers have equal torque applied thereto whereby a difference in speed between the drive shaft and said first propeller shaft due to unequal torques applied to the propellers will cause relative motion between the drive shaft gear and said pinions thereby to adjust the pitch of the rotatable blades sufficiently to equalize the torque on the propellers.

'7. Torque equalizing apparatus for counterrotating propellers arranged to be driven from a rotary drive shaft comprising, in combination, a pair of tandem propellers having oppositely pitched blades, means for supporting the blades of one of said propellers for rotation about the pitch axes thereof, means including differential driving connections for driving the propellers in opposite directions from said rotary drive shaft and at different speed differentials with respect thereto selectively in accordance with the difference in the torques on the propellers, said one of the propellers being driven in the direction of rotation of the drive shaft, and pitch changing gearing between said rotatable blades and the drive shaft for adjusting the pitch of the blades independently of the speed of rotation of the other of said propellers and in response to a speed differential between said one of the propellers and the drive shaft.

8. Torque equalizing apparatus for counterrotating propellers arranged to be driven from a rotary drive shaft comprising, in combination, a pair of tandem propellers having oppositely pitched blades, means for supportin the blades of one of said propellers for rotation about the pitch axes thereof, means including reverse driving connections for driving the other one of the propellers from the rotary drive shaft and in the opposite direction thereof, means including differential driving connections for driving said one of the propellers at different speed differentials with respect to the rotary drive shaft and in the same direction thereof selectively in accordance with the difference in the torques on the pro pellers, and pitch changing gearing between said rotatable blades and the drive shaft for adjust ing the pitch of the blades independently of the speed of rotation of the other of the propellers and in response to a speed differential between said one of the propellers and the drive shaft.

9. A propeller driving system for a torpedo comprising, in combination, a pair of propellers. one of said propellers having variable pitch blades,

' a pair of coaxially arranged propeller shafts individual to said pair of propellers, a drive shaft coaxially arranged with respect to said. propeller shafts and having a shaft portion extended adjacent said propellers, driving connections including differential gearing between said drive shaft and said pair of propeller shafts for driving the propellers in opposite directions at the speed of the drive shaft when the propellers have equal torques applied thereto, and pitch-changing gearing between said variable pitch blades and said extended portion of the drive shaft and controlled by said differential gearing for adjusting the pitch of the blades sufiiciently to equalize the torques on the propellers.

10. A system for driving a torpedo comprising, in combination, a pair of propellers, one of said propellers having variable pitch blades and the other of said propellers having fixed pitch blades, means including differential gearing for driving the propellers in opposite directions, and means including bevel gearing operatively connected to said variable pitch blades and controlled by the difference in torques on said pair of propellers and independent of the speed of rotation of the said propeller having fixed pitch blades for adjusting the pitch of said variable pitch'blades until the torques on the pair of propellers are equalized.

11. A system for driving a torpedo comprising, in combination, a pair of propellers, one of said propellers having variable pitch blades and the other of said propellers having fixed pitch blades, means including differential gearing for driving the propellers in opposite directions, and means including bevel gearing operatively connected to said variable pitch blades and responsive to a deviation in the speed of rotation of said one of the propellers from the speed of rotation of the other one of the propellers when the torques n the pairlof propellers are equal for adjusting the pitch of said variable pitch blades independently of the speed of rotation of the other of the propellers until the propeller speeds are equal.

12. A system for driving a torpedo comprising, in combination, a pair of propellers, one of said propellers having variable pitch blades, means including differential gearing and a drive shaft therefor for driving the propellers in opposite directions, and means including bevel gearing interconnecting said variable pitch blades and said drive shaft and responsive to a deviation in speeds of rotation of the drive shaft and said one of the propellers for adjusting the pitch of said variable pitch blades independenly of the speed of rotation of the other one of the propellers until the speed of rotation'of the drive shaft and propellers are equalized. i

THEODORE E. DINSMOOR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,835,849 Covey Dec. 8, 1931 2,216,013 Kenney Sept. 24, 1940 2,276,663 Mercier Mar. 17, 1942 2,480,806 Desmoulins Aug. 30, 1949 FOREIGN PATENTS Number Country Date 1 847,990 France July 17, 1939 

